ABSTRACT Recently, the AlB2-type compounds (such as AlB2 and MgB2) which exhibit Dirac Nodal Line (DNLs) semimetal on their electronic band structure and Phononic Weyl Nodal Straight Lines (PTWNLs) on their phonon spectrum, have received wide attentions on their novel properties. Up to date, no comparative studies have been investigated on their electronic structures, phonon spectrum, and electron phonon coupling (EPC) under the conditions of carrier doping and strain engineering. Here, we systemically investigate their above properties under carrier doping and strain engineering by first-principles calculations. The results show that the superconducting transition temperature T c can be enhanced by electron doping and tensile strain. For AlB2, the tensile strain of 6% can enhance T c to 10.25 K and with the doping concentrate of 0.1 e- per cell can enhance T c reach to 9.89 K. Moreover, the physical quantities related to superconductivity of AlB2 are more affected by carrier doping than MgB2. Our results provide a theoretical reference to explore the correlation between electronic and phonon topological properties in AlB2-type materials.

中文翻译：

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AlB2 和 MgB2：通过第一性原理比较研究它们的电子、声子和超导特性

摘要 近年来，AlB2 型化合物（如 AlB2 和 MgB2）在其电子能带结构上表现出狄拉克节线（DNLs）半金属，在其声子谱上表现出声子外尔交点直线（PTWNLs），因此受到了广泛的关注。特性。迄今为止，还没有对它们在载流子掺杂和应变工程条件下的电子结构、声子光谱和电子声子耦合（EPC）进行比较研究。在这里，我们通过第一性原理计算系统地研究了它们在载流子掺杂和应变工程下的上述特性。结果表明，电子掺杂和拉伸应变可以提高超导转变温度T c 。对于 AlB2，6% 的拉伸应变可以将 Tc 提高到 10.25 K，掺杂浓度为 0。1 e-per cell 可以将T c 提高到9.89 K。此外，与MgB2 相比，载流子掺杂对AlB2 超导性的影响更大。我们的研究结果为探索 AlB2 型材料中电子和声子拓扑特性之间的相关性提供了理论参考。